1. Field of the Invention
The present invention is generally related to communication systems. More particularly, the present invention is related to a cable modem system and a method and computer program product for providing Real Time Protocol header suppression across a DOCSIS network.
2. Background Art
Conventional cable modem systems utilize DOCSIS (Data Over Cable System Interface Specification) —compliant equipment and protocols to transfer data between one or more cable modems (CM) and a cable modem termination system (CMTS). DOCSIS generally refers to a group of specifications that define industry standards for cable headend and cable modem equipment. In part, DOCSIS sets forth requirements and objectives for various aspects of cable modem systems including operations support systems, management, data interfaces, as well as network layer, data link layer, and physical layer transport for cable modem systems.
Real-time Transport Protocol (RTP) is a protocol for delivering packetized audio and video traffic over an Internet Protocol network. RTP provides end-to-end network transport functions for applications with real-time requirements. Such applications may include audio, video, or simulation data over multicast or unicast network services. RTP is also used to send VOIP (voice over IP) phone calls.
An increasing number of applications are utilizing RTP to deliver voice and multimedia data streams. The data portion of an RTP packet is often small in comparison to the protocol overhead required to send the information. Current techniques for delivering RTP packets waste network bandwidth by sending redundant information. Also, current techniques do not allow for the suppression of changing RTP fields in a data stream.
DOCSIS 1.1 provides a technique for the suppression of redundant information called “payload header suppression” (PHS). PHS enables the suppression of unchanging bytes in an individual Service Identifier (SID) (i.e., data stream). Thus, DOCSIS PHS provides byte oriented suppression. Byte oriented suppression is not as efficient as a field oriented protocol header suppression scheme. Another downside to PHS is its inability to suppress dynamically changing fields in a data stream.
What is needed is a system and method for in order delivery of transmitted RTP packets that eliminates the transmission of redundant patterns. What is also needed is a system and method for in order delivery of transmitted RTP packets that provides a field oriented protocol header suppression scheme. What is further needed is a system and method for in order delivery of transmitted RTP packets that suppresses dynamically changing fields in a data stream.